Texas & Pacific 4-4-2 "Atlantic" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class E-1-s (Locobase 8494)

Data from T&P 1 - 1950ca Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange.

Although only 2 in number and home-built, these Atlantics followed the lines of the classic express locomotive in many respects. Although the boiler was relatively small in relation to the cylinders, the firebox ratios stood almost squarely in the middle of the more than 100 designs examined in this comparison. And a look at the profile shows large-diameter trailing wheels (51") under the firebox.

Unfortunately, says Drury (1993) "They turned out to be rear-heavy and unstable, and their 28,000 lb of tractive effort was no more than that of the considerably lighter D-9 Ten-Wheelers that preceded them."

Delivered as saturated-steam engines in 1906, they were superheated in 1917, at which time they were fitted with 14" piston valves and Southern valve gear. Thus equipped, they served the T & P for another decade.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID8494
RailroadTexas & Pacific (T&P)
Number in Class2
Road Numbers339-340
Number Built2
BuilderTexas & Pacific
Valve GearSouthern
Locomotive Length and Weight
Driver Wheelbase (ft / m)7 / 2.13
Engine Wheelbase (ft / m)27.58 / 8.41
Ratio of driving wheelbase to overall engine wheebase 0.25
Overall Wheelbase (engine & tender) (ft / m)56.87 / 17.33
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)123,900 / 56,200
Engine Weight (lbs / kg)213,986 / 97,063
Tender Loaded Weight (lbs / kg)114,879 / 52,108
Total Engine and Tender Weight (lbs / kg)328,865 / 149,171
Tender Water Capacity (gals / ML)6500 / 24.62
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)3000 / 11.40
Minimum weight of rail (calculated) (lb/yd / kg/m)103 / 51.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)75 / 1905
Boiler Pressure (psi / kPa)185 / 12.80
High Pressure Cylinders (dia x stroke) (in / mm)22" x 28" / 559x711
Tractive Effort (lbs / kg)28,414 / 12888.39
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.36
Heating Ability
Firebox Area (sq ft / m2)180 / 16.73
Grate Area (sq ft / m2)45 / 4.18
Evaporative Heating Surface (sq ft / m2)2470 / 229.55
Superheating Surface (sq ft / m2)525 / 48.79
Combined Heating Surface (sq ft / m2)2995 / 278.34
Evaporative Heating Surface/Cylinder Volume200.50
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation8325
Same as above plus superheater percentage9824
Same as above but substitute firebox area for grate area39,294
Power L115,196
Power MT540.78

All material Copyright © SteamLocomotive.com
Wes Barris